Move code to CollectionPackagerBase::internalCreatePackage(), instead. That's both before preArchive() gets called, and one level higher up the food-chain. I don't think the patch would apply to "non-collection" packagers (and it would not be trivial to add there), but perhaps I don't really understand, what these are used for.

Regarding fixing the installation dirs in the first place: Yes that would seem preferable, but I really don't know near enough to be comfortable with such a change. I do note that the problem is long-standing, too. What I'm looking for, here, is a pragmatic solution such that projects can in fact get going with creating standalone installers, without having to worry about any gory details. If a better solution is found, later, at least there will be only one place to fix up, not every single craft recipe.

When going into this, nonetheless, from the little understanding I have, I believe the problem is likely to be that Qt on Windows considers the topmost directory the "root", while KDE considers "bin" to be the root. I'm not sure this can be resolved, easily. Supplying qt.conf might be an option, though, and at any rate, its documentation seems to be pretty relevant info for any alternative attempts: http://doc.qt.io/qt-5/qt-conf.html .

Check paths for existence before moving.

Also, clean up existing workarounds in portage. Note that several port recipes also try to move paths like lib/plugins. I suspect those do not have any effect, but I have not touched those.